Golf club heads come in many different forms and makes, such as wood- or metal-type, iron-type (including wedge-type club heads), utility- or specialty-type, and putter-type. Each of these styles has a prescribed function and make-up. The present invention will be discussed as relating to iron-type clubs, but the inventive teachings disclosed herein may be applied to other types of clubs.
Iron-type and utility-type golf club heads generally include a front or striking face, a hosel, and a sole. The front face interfaces with and strikes the golf ball. A plurality of grooves, sometimes referred to as “score lines,” is provided on the face to assist in imparting spin to the ball. The hosel is generally configured to have a particular look to the golfer, to provide a lodging for the golf shaft, and to provide structural rigidity for the club head. The sole of the golf club is particularly important to the golf shot because it contacts and interacts with the playing surface during the swing.
Perimeter weighting in iron-type golf clubs distributes non-essential mass of the iron towards the perimeter, reducing the effects that off-center hits have on the golf club and producing more accurate and consistent golf ball trajectories. Perimeter weighting is achieved by creating a cavity in the back of the golf club opposite the face or hitting surface. The material weight removed to create this cavity is redistributed around the perimeter of the golf club head. In general, larger cavity volumes correspond to increased amounts of mass distributed around the perimeter.
Removing material from the rear of the club head, however, may reduce the thickness of the club face. Since the club face is the hitting surface, the club face cannot be so thin that the strength of the club face surface is not sufficient to withstand the stress resulting from the club face striking a golf ball. A reduction in the thickness of the club face may also increase the vibrational response of the club head upon impact of the club face with the golf ball, which may have unappealing vibration and deflection characteristics that adversely affect the feel of shots and the energy transfer to the golf ball during impact.
Golfers tend to be sensitive to the feel of a golf club, particularly feel of the club upon impact of the club face with the golf ball. Accordingly, some designers try to dampen these unappealing vibrations by adding an elastic material in the club head. There are various examples of secondary material incorporation into iron golf club heads for vibration damping. For example, some iron golf club heads include damping inserts fitted within the rear cavity of the club head and in contact with the back of the club face. Such inserts may be composed of a polymer, such as TPU (thermoplastic urethane), TPR (thermoplastic rubber), or other material capable of damping vibrations caused by club face impact with a golf ball. Some iron golf club heads include a damping system, such as constrained layer damping assembly, which may consist of, for example, a medallion composed of TPU, plastic, or metal attached to the back of an iron cavity using viscoelastic tape.
Although current damping inserts/assemblies are intended to provide vibration damping and improve the feel of the club, golfers may prefer to have some form of clear indication that such vibration dampening is actually occurring, rather than simply relying on a designer's advertised claim. As such, one drawback to current damping inserts/assemblies is that they fail to provide a means for a golfer to quantify the efficacy of the damping insert/assembly. Instead, a golfer is left to either assume the validity of a manufacturer's claim that their golf club has an effective damping means or compare a golf club with a damping element to a golf club without such a damping element so as to determine improved feel, if any.